The Unified Modeling Language (or UML) is a standard notation for modeling objects and their relationships and provides a consistent language for specifying, visualizing, constructing and documenting object-oriented software systems.
You can add UML class diagrams to classes or folders. UML class diagrams are elements that are shown in the class view and the Designer Window Members tab of the owning element.
UML class diagrams show relationships between classes, such as:
Inheritance, represented by an arrow line joining the two classes.
Simple dependency, represented by a dashed arrow line joining the two classes.
Association, represented by a line joining the two classes.
Aggregation, represented by a diamond at the end of the association next to the aggregate class.